4ETS:
reference: Structure and regulon of Campylobacter jejuni ferric uptake regulator Fur define apo-Fur regulation., Butcher J, Sarvan S, Brunzelle JS, Couture JF, Stintzi A, Proc Natl Acad Sci U S A. 2012 Jun 4. PMID: 22665794

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).